This invention relates to a liquid crystal display device and, more particularly, to a reflection-type liquid crystal display device used in portable information terminals, for example.
A reflection-type liquid crystal display device using external light as its light source can be greatly reduced in consumption power as compared with transmission-type liquid crystal display devices. Therefore, there is a demand for development thereof toward the use in various portable devices such as portable information terminals, for example.
Reflection-type liquid crystal display devices are required to have a view angle not smaller than 60.degree. under a predetermined condition. To deal with this requirement, the Inventors tried to employ an anti-glare film. That is, in a reflection-type liquid crystal display device, an anti-glare film for multiplex refraction of light from a liquid crystal layer is laid on the outer surface of a front substrate. The view angle can be increased by the film. This film simultaneously makes it possible to alleviate entry of external light caused by reflection from the surface the observer-side substrate (front substrate) on which displayed images are observed.
However, in the reflection-type liquid crystal display device using an anti-glare film, if the diffusion power is increased to ensure an ample view angle, letters on the display blur due to multiplex refraction. That is, deterioration of the display quality has been recognized as a problem.
Aside from it, the Inventors also tried to diffuse emitted light and expand the view angle by placing a single refraction layer for single refraction of light from the liquid crystal layer between the front substrate and the polarizing plate in a reflection-type liquid crystal display device.
However, in the case where the single refraction layer is interposed between the front substrate and the polarizing plate, when the refraction power is increased to obtain an ample view angle, the diffusion property gets weaker as the wavelength of light becomes longer, and wavelength dispersion occurs. It results in causing "coloring" which is the phonomenon where emitted light is recognized as different colors when observed from different angles. The Inventors has been aware of this problem through this trial.